A. Field of the Invention
The present invention relates to an endoscope including an insertion portion having a hard distal end portion and, more particularly, to an ultrasonic endoscope incorporating an ultrasonic vibrator at its hard distal end portion.
B. Description of the Prior Art
In a known ultrasonic endoscope, an ultrasonic vibrator for transmitting/receiving an ultrasonic wave is mounted on, e.g., a hard distal end portion of an insertion portion of the endoscope, and the ultrasonic wave is scanned by the ultrasonic vibrator, thereby observing, e.g., a tomographic image of a body cavity wall. In such an ultrasonic endoscope, a concave ultrasonic vibrator mounting portion for incorporating the ultrasonic vibrator, and insertion holes for receiving a bundle of optical fibers of an observation optical system, e.g., a light guide and an image guide, are formed in a main body of the hard distal end portion. The ultrasonic vibrator is fixed in the ultrasonic vibrator mounting portion of the hard distal end portion by an adhesive and the like, and the bundle of optical fibers of the observation optical system is fixed in the insertion holes of the hard distal end portion by an adhesive and the like.
As a conventional example, in an ultrasonic endoscope disclosed in Japanese Patent Disclosure (Kokai) No. 57-200136, a bundle of optical fibers of an observation optical system, e.g., a light guide and an image guide, is embedded in a support block, an ultrasonic vibrator is placed in a space of a housing portion of the support block, and a filler material is filled in a space around the ultrasonic vibrator, thereby fixing the ultrasonic vibrator integrally with the support block.
In addition, in an ultrasonic endoscope disclosed in Japanese Utility Model Disclosure (Kokai) No. 57-26207, a recess for incorporating an ultrasonic vibrator is formed in a main body of a distal end constituting portion, and insertion holes for receiving a bundle of optical fibers such as an image guide of an observation optical system and a light guide of an illumination optical system are formed in the distal end constituting portion. The ultrasonic vibrator is fixed in the recess by an adhesive and the like, and the bundle of optical fibers is inserted in the insertion holes and fixed therein by an adhesive and the like. That is, the ultrasonic vibrator, the bundle of optical fibers, and the like are fixed in the main body of the distal end constituting portion, respectively.
Furthermore, in an endoscope disclosed in Japanese Patent Disclosure (Kokai) No. 55-96132, an ultrasonic vibrator is detachably mounted on the distal end of a distal end constituting portion by an electrical connecting means such as a connector.
A large number of signal cables are connected to a typical ultrasonic vibrator. In addition, a plurality of pipes such as an air-supply channel and a treatment tool insertion channel together with optical fibers of an observation optical system are housed in an insertion portion of an endoscope. For this reason, when a signal cable of the ultrasonic vibrator is disposed in the insertion portion of the endoscope, an inner space of the insertion portion becomes extremely small. Therefore, when the insertion portion is to be bent during an operation of the endoscope, the bundle of optical fibers, the pipes, and the signal cables of the ultrasonic vibrator disposed in the insertion portion interfere with each other, thereby posing a problem in which the bundle of optical fibers is cut.
However, in a conventional ultrasonic endoscope, the ultrasonic vibrator and the bundle of optical fibers of the observation optical system are fixed integrally with each other in the main body of the hard distal end portion. Therefore, when the bundle of optical fibers of the observation optical system is damaged, the expensive ultrasonic vibrator which normally operates must be replaced together with the damaged bundle of optical fibers, resulting in high cost.